Today in History is a daily newsletter from Britannica. (more) Today in History—March 31: How WWI Invented Daylight Saving Time Written by Michele Metych Michele Metych is the lead editor for Today in History at Encyclopædia Britannica. Michele Metych Fact-checked by Britannica Editors Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... Britannica Editors Last updated Mar. 27, 2026 •History World War I was raging, and countries were increasingly desperate for coal—desperate enough to bend time. Today in History is a daily newsletter from Britannica.Encyclopædia Britannica, Inc. Want to learn more about what happened on March 31, or any other day of the year? Sign up to receive the newsletter in your inbox every morning. The idea was simple: Stretch limited supplies of oil and gas by reducing consumers’ use of artificial light by shifting the clock...

　　.eb-448-paywall-overlay { position: relative; background: white; border: 2px solid #93c5fd; border-radius: 16px; text-align: center; box-shadow: 0 4px 8px 0px #bfdbfe; width: 100%; overflow: hidden; } .eb-448-paywall-overlay-padding { padding: 40px 48px; } .eb-448-paywall-simple { border: 2px solid #93c5fd; } .eb-448-decorative-left-simple, .eb-448-decorative-right-simple { position: absolute; top: 50%; transform: translateY(-50%); } .eb-448-decorative-left-simple { left: 0px; transform: translateY(-50%) scaleX(-1); } .eb-448-paywall-simple .eb-448-decorative-right-simple { right: 0; } .eb-448-paywall-content { position: relative; z-index: 15; } .eb-448-header-section { display: flex; align-items: center; justify-content: center; gap: 12px; margin-bottom: 8px; } .eb-448-features { display: flex; justify-content: center; align-items: center; gap: 12px; margin-bottom: 32px; font-size: 14px; color: #525252; } .eb-448-features-simple { color: #6b6b6b; } .eb-448-feature-free-trial { display: flex; align-items: center; gap: 12px; color: black; } .eb-448-feature-secondary { display: flex; align-items: center; gap: 12px; } .eb-448-feature { font-weight: 600; } .eb-448-feature.simple { font-weight: 400; } .eb-448-feature.bold { color: balck; font-weight: 700; } .eb-448-feature.blue { color: #14599d; } .eb-448-divider { color: #cbd5e0; font-weight: 300; } .eb-448-unsubscribe-text { color: #525252; margin-bottom: 8px; font-size: 14px; font-weight: 600; } .eb-448-unsubscribe-text-simple { font-weight: 400; color: #6b6b6b; } .eb-448-decorative-left { position: absolute; top: 0; left: 0; height: 100%; z-index: -1; } .eb-448-decorative-right { position: absolute; right: 0; top: 0; height: 100%; } .eb-448-decorative-image { height: 100%; } .eb-448-decorative-mobile { width: 100%; display: none; img { width: 100%; } } @media (max-width: 672px) { .eb-448-features { gap: 8px; font-size: 12px; } .eb-448-unsubscribe-text { font-size: 12px; } .eb-448-decorative-left, .eb-448-decorative-right { display: none; } .eb-448-decorative-mobile { display: flex; } .eb-448-paywall-overlay-padding { padding: 20px 24px; } .eb-448-features-simple { flex-direction: column; } .eb-448-feature-free-trial .eb-448-divider { display: none; } .eb-448-thistle-icon { filter: blur(2px); } }

　　Discover the world with Britannica Subscribe to Continue Reading Free Trial | No Ads | Exclusive Content Unsubscribe Anytime!

　　Explore Subscriptions